{"id":319873,"date":"2023-11-28T22:14:34","date_gmt":"2023-11-28T22:14:34","guid":{"rendered":"\/forum\/forums\/topic\/why-negative-moment-wind-turbine-residuals\/"},"modified":"2023-11-28T22:14:34","modified_gmt":"2023-11-28T22:14:34","slug":"why-negative-moment-wind-turbine-residuals","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/why-negative-moment-wind-turbine-residuals\/","title":{"rendered":"Why Negative Moment &#8211; Wind Turbine &#8211; &amp; Residuals"},"content":{"rendered":"<p>Hello Forum,<\/p>\n<p>I am wondering why I am getting negative moment values for a Darrius type vertical axis wind turbine when there is constant counterclockwise rotation. The Motion History data in Fluent shows constant CC motion, yet the moment plot is cyclic with positive and negative values. See attached pic.&nbsp;<\/p>\n<p>I am using dynamic mesh and the three airfoils are treated as one unit&#8230; the turbine&#8230; which is defined to rotate in the 6DOF settings.<\/p>\n<p>By any chance, anyone have any thoughts why the negative moment values exist and how to correct it?&nbsp;<\/p>\n<p>Also, do the residuals look good? I don&#8217;t see much of a reduction in value from start to finish (but my impression is that wind turbines don&#8217;t share this outcome)&#8230; although the time interval from high to low cycles does shorten with time (the zigzag is more prominant) in the latter 1\/2 of the flow time.<\/p>\n<p>Thanks, Nate<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/11\/28-11-2023-1701208841-mceclip0.png\" width=\"895\" height=\"449\"><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/11\/28-11-2023-1701208950-mceclip2.png\" width=\"851\" height=\"496\"><\/p>\n<p>&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/11\/28-11-2023-1701209383-mceclip5.png\" width=\"836\" height=\"418\"><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/11\/28-11-2023-1701209252-mceclip4.png\"><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"template":"","class_list":["post-319873","topic","type-topic","status-closed","hentry","topic-tag-6dof-solver","topic-tag-fluent","topic-tag-moment","topic-tag-wind-turbine"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["18237","199"],"_bbp_author_ip":["23.52.43.10"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["586"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["319873"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","18237"],"_bbp_voice_count":["2"],"_bbp_reply_count":["7"],"_bbp_last_reply_id":["326385"],"_bbp_last_active_id":["326385"],"_bbp_last_active_time":["2023-12-05 10:00:15"]},"test":"nate-kuenzistmartin-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/319873","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/319873\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=319873"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}